Global plant trade may increase risk of alien diseases |
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According to the RHS Advisory Department, the number of plant disease outbreaks is up by 60 percent on last year. Increased global plant trade, coupled with evidence of rapid climate change, suggests that the problem will only get worse. Recent Defra reports have highlighted the worrying spread of disease on rhododendrons in the south west of England caused by Phytophthora ramorum and Phytophthora kernoviae (pictured), while many other diseases, including box blight (Cylindrocladium buxicola), which is responsible for the destruction of box hedges, and Dutch elm disease (Ophiostoma novo-ulmi), are well known for the problems they cause. The report, Non-native diseases and the future of UK gardens, proposes that the horticultural industry worldwide develops effective systems to manage the risks that growing and trading of ornamental plants are now creating. Suggested features of such a system would be similar to those, driven by supermarkets, that are now familiar in relation to food assurance schemes. The report suggests that new quality assurance systems, driven by a voluntary code of conduct, could sit alongside the current UK plant inspection programme and offer further reassurances to plant buyers. In 2005, £870 million was spent on imported plants by the British public. The current inspection scheme only applies to plants known to play host to diseases and does not provide the opportunity to capture evidence of new diseases symptoms. Dr Simon Thornton Wood, Director of Science and Learning at the RHS, explains: “The current plant inspection programme works exceptionally well for diseases we already know about. But it is the unknown diseases, on plants that would not normally be considered problematic, that are the real cause for concern. Phytophthora kernoviae and P. ramorum entered the UK because they were not known about and so not checked for. They have wreaked havoc with cultivated rhododendrons. “However, an industry code of conduct could provide the answer, with every stage of the production and transport process managed with disease risk in mind. We would then be able to avoid another situation like sudden oak death or Dutch elm disease that has changed the face of the Britain’s countryside.” Striking the balance between plant health and providing the variety of plants that inspire this nation of gardeners, is at the forefront of the RHS’ mind. We believe that gardeners' awareness could be the key to ensuring that a code of conduct, underpinning true quality assurance, is developed by the plant importing trade. Dr Simon Thornton Wood continues: “Working together gardeners can help the RHS to track the emergence and spread of pest and disease problems and together we can all take responsibility for the health of our gardens and the wider environment. Everyone has an interest in ensuring that high-quality, disease-free plants arrive at our shores and reach our gardens.” A Defra consultation on the problem of Phytophthora was launched at RHS Garden Wisley on 15 July 2008. View the full report (96KB Adobe Acrobat pdf) The RHS position on alien pests and diseases (16KB Adobe Acrobat pdf) |
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Alien pests and diseases, inadvertently imported on exotic plants, are threatening the plants in our gardens and across the countryside, according to a report launched by a scientific working group led by the RHS.